1. 3g. describe the addition polymerization of alkenes and identify the repeat unit given the monomer, and vice versa Crowe2008 Addition polymerization of alkenes Connector - Draw the major addition products for the reactions between i) Br 2 & ii) HBr with: propene, but-1-ene, but-2-ene, and 2-methylpropene

2. C – C CH HHH H H Br C – C CH HHH H H HBr C C H HHH H H H H Br C C H HHH H H H H BrH Markovnikov addition

3. C C H HHH H H H Br H C C H HHH H H H H BrH C HCH 3 H Br C HCH 3 H HBr Markovnikov addition

4. Monomers and Polymers Ethene Ethene is called a MONOMER because it is just one small molecule. We can use ethene to make plastics… Step 1: Break the double bond Step 2: Add lots of the molecules together: This molecule is called POLYETHENE, and the process that made it is called POLYMERISATION

5. Manufacture of addition polymers. An addition reaction is one in which two or more molecules join together to give a single product. During the polymerisation of ethene, thousands of ethene molecules join together to make poly(ethene) - commonly called polythene. The number of molecules joining up is very variable, but is in the region of 2000 to 20000. Conditions Temperature: about 200°C Pressure: about 2000 atmospheres Initiator: a small amount of oxygen as an impurity

6. HH CC H HH HH C C HH HH CC HH HH CC HH HH CC HH And lots more.. addition polymerisation This is called addition polymerisation and is written as: Pressure high temperature catalyst n n ethene poly(e)thene 1 2 3 4 5 thousands Another way of drawing it… n = a large number

7. Draw the equations for the polymerisation of the following alkenes and name the polymer: C C n H CH 3 H H n tetrafluoroethene Poly(tetrafluoroethane) or PTFE n propene

8. n tetrafluoroethene Poly(tetrafluoroethene) or PTFE n Poly(propene) n n propene CH 3

9. You may be asked to show polymerisation using three or more monomer units. e.g. Draw a similar process for propene and chloroethene

11. Thermosoftening polymers or thermoplastics: weak intermolecular forces – these let the chains slide past each other These soften when heated and can be remoulded into new shapes

12. Plastics made of these polymers cannot be stretched, are rigid and have a high melting point. They are called thermosetting plastics (or ‘thermosets’). strong intermolecular forces (cross-links) – these hold the chains firmly in place Some polymer chains cannot slide past each other. What are thermosetting plastics?

13. Homework - Research the problems and solutions wrst the use of polymers. You should include the following key areas: Energy costs sources Resources used Disposal problems biodegradable polymers Carbon footprint Recycling/reusing

14. Use the above data to compare the properties of PLA with polystyrene and PVC. Produce graphs to show the tensile strength, elastic modulus and tear strength as both hard sheets and soft films. How does PLA compare with conventional polymers?

15. hard sheetssoft films

16. Life cycle analysis

17. Life cycle analyses of three different materials for gas pipes cast ironpolythenePVC POCP216 215 ECA266.43.9 GWP312221 AP132.51.1 ADP9.710.45 HT141.90.76 NP2.50.610.33 OTL110.390.48 ODP1.250.170.07 EC748303139 Present the information in the form of a bar chart so that the environmental features may be compared. Suggest why the scientists may have been surprised by their findings.

18. Life cycle analyses of three different materials for gas pipes Suggest why the scientists may have been surprised by their findings. cast ironpolythenePVC